1. Field of the Invention
The present invention relates to a complex electronic component to be used for, for example, mobile communication devices, especially to a complex electronic component in which a surface acoustic wave element is mounted in a concave portion of a multilayer substrate and a filter comprising a passive element is disposed within the multilayer substrate.
2. Description of the Related Art
FIG. 4 shows a common cross section of conventional complex electronic components 50 provided with a multilayer substrate 51 inside of which a LC filter is disposed. A concave portion 52 is provided on the top surface of the multilayer substrate 51 and a surface acoustic wave filter 53 as a bare chip is mounted inside of the concave portion 52, an IC 54 and a capacitor 55 being mounted on the top surface of the flat portion of the multilayer substrate 51 except the concave portion 52. The concave portion 52 is covered with a flat cap 56 made of a metal.
However, a concave portion for mounting the surface acoustic wave element and a flat portion for mounting the IC and capacitor should be provided on the top surface of the multilayer substrate in the conventional complex electronic component as described above. In other words, the size of the multilayer substrate becomes large due to two-dimensional arrangement of a plurality of components on the top surface of the multilayer substrate when the number of the component is increased, causing a problem that the size of the complex electronic component also becomes large.
The object of the present invention, carried out for solving the foregoing problems, is to provide a complex electronic component capable of being compacted.
The preferred embodiment of the present invention provides a complex electronic component, comprising; a multilayer substrate formed by laminating a plurality of dielectric layers; a first concave part being provided at least at the bottom surface of said multilayer substrate; a filter comprising at least one first passive element disposed within said multilayer substrate; an external terminal provided on at least one of the flat portion of the bottom surface and the side face of said multilayer substrate; either one of an active element or a second passive element mounted on the top surface of said multilayer substrate, a surface acoustic wave element mounted inside of said first concave portion of said multilayer substrate; and a flat cap provided at the opening of said first concave portion of said multilayer substrate so as to cover said opening said first concave portion.
According to the above described complex electronic component, since either one of the active element or the passive element is mounted on the top surface of the multilayer substrate accommodating a filter comprising a passive element and the surface acoustic wave filter is mounted in the concave portion provided on the bottom surface of the multilayer substrate, the function required for the multilayer substrate can be allotted to the top and bottom surfaces to compact the multilayer substrate accommodating the filters. Consequently, the complex electronic component can be made compact thereby compacting the mobile communication device mounting the complex electronic component.
The above described complex electronic component may further comprise a second concave portion on said top surface of said multilayer substrate, and either said active element or said second passive element may be mounted on said second concave portion.
In the above structure, since the second concave portion is provided on the top surface of the multilayer substrate accommodating a filter comprising the passive element and either one of the active element or the passive element is mounted in the second concave portion, the height of the multilayer substrate can be made low, allowing the complex electronic component to be low height to result in a more compact size. Consequently, the mobile communication device mounting the complex electronic component becomes more compact.
Other features and advantages of the present invention will become apparent from the following description of the invention which refers to the accompanying drawings.